Answer from whalesniper
Tickets enable extreme interoperability across different rollups.
There will likely be a generic wrapping service that takes any
FA1.2/FA2 and gives you a standard ticket that can be used on any
rollup. The job of rollup creators will be to use the same service so
that users dont have to keep wrapping and unwrapping the same asset.
Rollups can be common goods but they don't have to. For example,
EVM Kernel? Common good. Anyone can bring solidity contracts to this
rollup and have fun.
Game Kernel? More private. Game logic will likely be specific for a
specific game. So a custom kernel will be more appropriate.
There's nothing wrong with paying for computation, and gas tokens are
feasible ways to do that. Gas tokens would be a MUST for the "common
good" rollups like a big EVM kernel.
Answer from daniel hines
In short, you can write your own rollup kernel to do whatever you
want. You could create your own token for gas on your rollup. However,
s Ctez is really useful in the context of rollups - it allows Tezos to
move assets to L2 and reap the benefits of better performance/lower
fees/etc. while not diluting/sacrificing their governance power.
Answer from nomadic labs
Nothing prevents a Smart Rollup from using its own token. However,
using ctez as a universal token for all rollups would make exchanges
between rollups smoother.